Machine tool



Dec. 12, 1944. H. c. WARNER ETAL 2,364,932

MACHINE TOOL Original Filed March 29, 1937 5 Sheets-Sheet l Dec. 12,1944. H. c. WARNER ET AL MACHINE TOOL 5 Sheets-Sheet 2 Original FiledMarch 29, 1957 3nmmtom WC. W M/M Q M 17 /V 4 attorney's Dec. 12, 1944.H. c. WARNER ETAL MACHINE TOOL Original Filed March 29, 1937 5Sheets-Sheet 3 Summers Dec. 12, 1944. H. c. WARNER ET AL 72,364,932

MACHINE TOOL Original Filed March 29, 1937 5 Sheets-Sheet 4 10.9 706 108I l 100 /J l'momtors 52 a w /1M 04 A Z w m H. C. WARNER ET AL MACHINETOOL Dec. 12, 1944.

Original Filed March 29, 1937 5 Sheets-Sheet 5 Enventors vmflga MW z csw52 m (Ittomegr Patented Dec. 12, 1944c MACHINE TOOL Homer 0. Warner andCharles H. Schurr, Cleveland, Ohio, asslgnors to The Lees-BradnerCompany, Cleveland, Ohio, a-corporation of Ohio Original applicationMarch 29, 1937, Serial No. 133,554. Divided and this application March20, 1940, Serial No. 325,028

I 9 Claims.

This invention relates to a machine tool particularly adapted forcutting'irregular or noncylindrical objects such, for instance, as gearteeth.

An object of the invention is to provide an improved machine tool whichwill be highly efficient in operation.

Another object is to provide an improved machine tool which will requirelittle attention.

Another object is to provide an improved machine tool which will beeconomical of floor space.

Another object is to provide an improved machine tool which will berapid and accurate in its operation.

Other objects will hereinafter appear.

The invention will bebetter understood from the description of onepractical embodiment thereof, illustrated in the accompanying drawings,in which:

Figure l is aside elevational view of the machine embodying theinvention, parts being broken away and shown in section;

Figure 2 is a sectional view taken on a plane parallel to Figure 1 asindicated by the line II-II of Figure 3;

Figure 3 is a fragmentary sectional view taken on the line III-III ofFigure 1;

Figure 4 is a fragmentary sectional view taken on the line IV-IV ofFigure 3;

Figure 5 is a fragmentary sectional view taken on the line VV of Figure3;

Figure 6 is a fragmentary sectional view taken on the line VI--VI ofFigure 8; v

Figure 7 is a fragmentary sectional view taken on the line VII-VII ofFigure 1;

Figure 8 is a fragmentary sectional view taken on th line VIII-VIII ofFigure 5;

Figure 9 is a perspective diagrammatic view of the gear trainsillustrated in the preceding figures;

Figure 10 is a fragmentary sectional view of the slide actuatingmechanism taken on line X-- X of Figure2;

Figure 11 is 'a diagrammatic illustration of the electrical circuitscontrolling the parts above illustrated; and

Figure 12 is a sectional fragmentary view illustrating the manner ofmaking a cut.

This application is a division of our copending application, SerialNumber 133,554, filed March 29, 1937.

The machine illustrated consists of a supporting base I upon which ismounted a frame 9 carrying the working parts of the machine.

The base I may be a stationary pedestal as illustrated, or it may be arotating turntable such 5 as illustrated in our application, SerialNumber 567,276, now Patent Number 2,075,489, which was copending withthe above mentioned application, of which this is a division,corresponding to the rotating base or table 2 of this application which10 extends laterally from the center hub or flange 4 shown in saidapplication.

The frame 2 is formed with upwardly extending ways 3, upon which areslidably mounted the tool head and its associated parts, to be herein-15 after further described, and also includes a hollow projecting casingportion 4 in which is journalled the work spindle, and which carriesparts of the mechanism which control and operate said spindle.

In addition, vertical ways 5 are formed upon the frame and upon these iscarried a tailstock t.

Mounted upon the base I is the main drivin motor 1, shown as providedwith a pulley 8 from which belts 9 pass to a pulley l0 secured to the 2end of a horizontal shaft ll journalled in the frame. Also secured tothe shaft II are a bevelled gear l2 and a spur gear l3, from the formerof which power is transmitted to the cutter or tool, and from the latterit is transmitted to the work and feed mechanisms.

Mounted in hearings on the frame is a vertically extending shaft l4,having keyed to its lower end a bevelled gear l5, meshing with abevelled gear l2, and also having keyed to it a pulley i8 for drivingthe pumping mechanism which will be hereinafter described.

The upper end of the shaft I4 is splined as indicated at I1, andslidable upon it is a bevelled gear l8 which is mounted in bearings in aver- 40 tically movable carriage is engaging and slidable up n the abovereferred to ways 3.

The carriage I9 is itself provided with horizontal ways 20 upon which ismounted a horizontally movable slide 2|,

A horizontal shaft 22 is mounted in bearings.

upon carriage l9 and provided with a bevelled gear 23 meshing with gearl8. This shaft is splined to t lescopically engage with anotherhorizontal shaft 24 having complementary splines and mounted in bearingswithin the slide 2|.

The end of shaft 24 remote from shaft 22 has formed integrally with it abevelled gear 25 which meshes with a bevelled gear 28 carried by a toolsupporting head 2'! which is secured to the end of the slide 2| byboltsor the like, so as to be angularly adjustable about the axis of shafts22 and 24.

' This gear is keyed to a shaft 28 which, through reduction gearing 29,drives a gear 30 keyed to the cutter spindle 3| which is supported inbearings in head 21 parallel to shaft 28 and is shown provided with ahob 32.

Meshing with gear i3 is a gear 33 splined to a horizontal shaft 34journalled in the frame 2 and extending through housing 4. The outer endof this shaft is provided with a change gear 35 which drives, throughchange gears 36 and 31, a horizontal shaft 39.

An idler 38 meshes with gear 35 and withra gear 40 secured to ahorizontal shaft 4| to which is also keyed a gear 42, forming a part ofa differential mechanism most clearly shown in Figure 4 to an enlargedscale.

The differential mechanism includes idlers 43 journalled in a cage 44,supported by a shaft 45 coaxial with shaft 4| and driven by means to behereinafter explained, and also a gear 45 fixed to a hollow shaft 41surrounding shaft 4| and provided with a worm 48 which meshes with aworm wheel 49.

The worm wheel 49 is keyed to a vertically extending work spindle 50mounted in suitable bearings in housing 4.

From the above, it will be apparent that when motor 1 is operated, itdrives, through pulley 8, belts 9, and pulley I 0, the shaft I I. Tothis is positively connected, by gears l2 and i5, shaft l4, gears i8 and23, shafts 22 and 24, gears 25 and 25, shaft 28, and gears 29 and 30, thcutter spindle 3|. Hence there is imparted to the cutter 32 a rotationwhich is always in fixed relation to the rotation of shaft Also, poweris transmitted from shaft ll through gears l3 and 33; shaft 34; gears35, 38, and 48; shaft 4|; gears 42, 43, and; shaft 41; worm 48; and wormwheel 49, to the work spindle 50, this rotation also being directlyrelated to the rotation of shaft excepting for any variation which maybe produced by rotation of differential cage 44 by shaft 45.

Thus the two trains of gearing already described produce the properrelative rotation of hob and work which would be necessary to generategear teeth upon a work blank mounted on spindle 50, and if the gear tobe produced is of the ordinary spur type having teeth parallel its axis,in which case no increment of rotation need be added to the difierentialmechanism referred to, but it would be only necessary, if the face ofthe gear were wide, to provide an axial feed or lead movement of thecutter relative the work in the di-.

rection of the axis of the latter.

However, as it is desired that the machine tool may be used in theproduction of other types of products, such as gears having helicallydisposed teeth, means have been provided for imparting an increment ofrotation related to the relative position of the tool axially of thework.

As previously mentioned, the change gears 35 and 31 drive a horizontalshaft 39 mounted within the frame of the machine. This shaft is providedwith a worm meshing with a worm wheel 52 secured to a shaft 53horizontally journalled in the frame and extending transversely of themachine, as most clearly shown in Figures 2, 8, and 9.

Keyed to the shaft 53 is a gear 54 which meshes with a gear 55 securedto a shaft 55 parallel to shaft 53 and journalled in the frame. Alsosecured to shaft 55 is a bevelled gear 51 forming a part of a seconddifferential mechanism.

This differential mechanism comprises a bevelled gear 58 opposed to gear51 and secured to a shaft 59 coaxial with 'shaft 55, the two bevelledgears meshing with bevelled pinions 45 carried in a cage II on theexterior of which is formed a worm wheel 52. Meshing with the worm wheel52 is a worm '53 flxedto the shaft 54 of an electric motor 55.

Keyed to shaft 59 is a skew gear 55 meshing with a second skew gear 51secured to a shaft 58 which extends to the exterior of the frame. Hereit is connected with a parallel shaft 59 by change gears 10, these beingenclosed within a cover 1|.

The shaft 59 has keyed to it, adjacent its end remote from change gears10, a skew gear 12 which meshes with a skew gear 13 formed upon a leadscrew 14.

This lead screw is threaded through a nut 15 secured to carriage I3 andserves to impart vertical lead or feed movement to the tool bycontrolling the motion of the carriage up and down upon ways 3.

It will thus be seen that, through skew gears 12 and 13, shaft 59, gears10, shaft 58, skew gears 55 and 51, shaft 59, bevelled gears 51, 58, and50, shaft 55, gears 54 and 55, shaft 53, and worm 5| and worm wheel 52,and gears 35, 35, and 31, the lead screw is positively connected back toshaft 34, which drives the work spindle, and that if motor 55 remainsstationary, the rotation of screw will be in direct proportion to therotation of shafts ii and 34.

If, however, motor 55 is rotated, it rotates bevelled pinions 60,through worm 53 and worm wheel 52, adding an increment of rotation tothe movement of screw in addition to the rotation caused by the driveshaft Formed on shaft 59 is a worm 15 which meshes with a worm wheel 11secured to a transverse horizontal shaft 18. This shaft extends throughthe frame, passing beneath worm wheel 49, to the exterior of the frame,where it is provided with a gear 19, which drives, through change gears80, a gear 8|. These gears are enclosed within a cover 82 secured to theframe.

Gear 8| is keyed to a shaft 83 extending within the frame provided witha worm 84 meshing with a worm wheel 85.

The worm wheel 85 is fixed to shaft 45 which, as above mentioned,carries the cage of the differential mechanism shown in Figure 3. Itwill thus be seen that this cage is positively geared to the shaft 59and so is controlled in its motion in accordance with the lead Or feedof the tool axially of the work.

By suitably selecting change gears 80, the cage 44 may therefore berotated to add any desired increment to the rotation of the work spindlein proportion to the axial travel of the tool, thus simply providing forproducing gears of any desired helix angle.

If gears having teeth parallel to their axes are desired, the changegears may be omitted, and the worm 84 locked against rotation, which maybe accomplished by having a low pitched worm which will be self-locking,or by any other desired means.

Motor 1 is of relatively high power and low speed in comparison withmotor 55, as its function is to drive the mechanism while performing itswork, while the function of the latter men'- tioned motor is to drivethe parts on part of their return, and it may therefore be of less pover and drive at'a higher speed,

When motor I is being actuated and motor 85 is stationary, the latter,having a low-pitched worm at 63, locks the cage 82 against rotation, sothat differential mechanism at this point acts merely as a setof idlergears, the various drives from shaft II being as above described.

When, however, motor I is allowed to remain stationary and motor 68 isoperated, cage 82 is driven by worm 83. Worm locks, due t its low pitch,worm wheel 52 and shaft 53. Power is therefore transmitted through gears50, 58, 6 8, 61, and to shaft 68, which through gears I2 and I3 operatesthe elevating screw, and at the same time through worm I8, worm wheel'I'I, gears I9, 80, and 8I, and worm and worm wheel 84 and 85 impartsthe necessary increment to the rotation of work spindle to correspondwith the elevation caused by the screw.

As best illustrated in Figures 1 and 2, the tail stock consists of aslide 6 mounted upon vertical ways 5 on the frame. This tail stock isprovided with a dead center 88 and with means for clamp-.

ing the stock in place consisting of a bolt or cam provided with anactuating handle 81. The dead center is, of course, in axial alinementwith the work spindle 50.

The base I is provided with an upwardly extending marginal flange 88which forms a trough upon the top of the base adapted to catch coolantand direct it into the hollow of the base which constitutes, in effect,a tank for this material. Within this hollow of the base is a pump 89provided with a vertically extending shaft 90 supported in a colurrm orpedestal 9| which extends above the base. The upper end of the shaft isprovided with a pulley 92 around which passes a belt 93 and is drivenfrom pulley I5 mounted on shaft I4. The belt is maintained taut by anidler pulley 94 adjustably carried upon an arm 95.

A cover 96 is secured to the frame and encloses gears 35 to 38 and 40.

Mechanism for feeding the cutter into depth is shown as comprising astop against which the horizontally moving slide may be pressed.

This stop consists of a rod 91 threaded into a threaded boss 98 formedon the vertically slidable carriage and provided with a squared end 99by which it may be adjusted. In alinement with this stop is a plungerI00 provided with compressed coil spring IOI arranged to move thehorizontal slide against the stop.

The plunger is also provided with ashoulder I02 for engaging a shoulderwithin the slide for withdrawing the slide from the stop whenreciprocation takes place in the opposite direction.

This plunger has a projecting lug r trunnion I03 entering a cam grooveI04 cut in a gear journailed on the vertical slide, this gear beingdriven by a pinion I06 made integral with a worm wheel I01 which isengaged by a worm I08 carried by the shaft of an electric motor I09fixed to the vertical slide.

The opposite side of the gear I05 has a somewhat similar cam groove I I0capable of actuating a sliding plunger I I I which operates switchescontrolling the motor I09 carried by the vertical slide and enteringinto circuits controlling motors I and 85 to be hereinafter described.

It will thus be apparent that when the gear I05 is rotated, untiltrunnion I08 is moved into the part of the cam groove remote from thecenter of the gear, the slide is moved to the right (as seen in thedrawings) and is pressed firmly against the stop rod 91, the spring IOIbeing further compressed during this action.

When the gear I05 rotates to bring the trunnion I03 into the innerportion of the cam groove, the slide is retracted toward the left (asseen in these figures), the spring IOI expanding to cause the shoulderI02 to bear upon the internal shoulder formed in the recess in which therod may reciprocate.

Similarly, when the slide has reached its extreme position, either tothe right or the left, the switch actuating rod III is reciprocated tostop the motor until after the vertical movement which follows feedinginto depth or retraction therefrom takes place.

The vertical slide is supported by a compression spring H2, shown asdisposed within telescopic tubular covers H3 and III and positionedbetween the base and the slide.

This spring is of suillcient strength that it more than supports theweight of the carriage and associated parts and causes this to exert anupward pressure at all times upon the thread of feed screw I4.

The feed of the cutter through the work is really accomplished by thespring, while the feed screw, instead of causing the cutter to movethrough the work, restrains this motion therethrough, acting as apositive stop of constantly continuously decreasing length.

This also eliminates any backlash in the feed, as the spring holds thescrew tight against its bearings. These bearings constitute, in effect,a positive stop fixed with respect to the frame.

Inasmuch as the movement of the hob toward the axis of the work ispositively and definitely limited by the stop 91!, and as the upwardmovement of the carriage is very positively and rigidly controlled bythe upward pressure upon the threads of the lead screw, it is possibleto cutin a manner different from that which has heretofore beenemployed.

With the parts arranged as shown in the drawings, a hob 32 is providedhaving teeth T arranged to cut when turning in clockwise direction, asseen in Figures 1, 2 and 12 and indicated by arrow R, and the cuttingfeed of the hob relative the work W is caused to operate in an upwarddirection as shown by arrow F. This causes the hob teeth to enter thepiece of work from their cylindrical outer surface s inwardly, startingat a relatively large angle to this surface and cutting in an obliquedownward direction. As the cut progresses, the hob risesor climbs alongthe work, always starting to cut at the periphery of the work, ratherthan as has been heretofore the practice, at the bottom of the partpreviously cut.

Thus each tooth of the hob passes at a relatively obtuse angle into thesurface of the work, starting its cutting action as soon as it contactsthe metal of the work, instead of tending to at first approach the workat a very acute angle and slide over the same, creating friction, whichimpairs the cutting edges.

With previous types of hobbing machines, this cutting would be extremelydiflicult, if not impossible, because of the tendency of the cutter topull itself forward, as it is acting in the same direction of the feed,thus gouging and otherwise mutilating the work.

The having of the cutting edges of the hob teeth move in the directionin which the hob is being fed, rather than in the opposite direction, isfound to very substantially prolong the life of the cutter betweensharpenings, and thus to increase the speed of production of themechanism.

As previously mentioned, the rod on the vertical slide is arranged tooperate switching means, these consisting of a switch A which will beopened when the horizontally movable slide is at its extreme right handor full depth position, and a switch B which; will be opened when It isat its extreme left hand or retracted position. Additionally switches Cand D are carried by the frame, the former being opened when the partsare in position to start cutting, and the latter when they are inposition at the end of a cut.

Additional safety, overload, and manually operable switches areprovided, as are relays for starting and controlling the motors.

These parts are all diagrammatically illustrated in Figure 11 while thestructure of the parts themselves will be readily understood, so

that only the circuit and the cycle of operation will be described.

Power is received from any suitable source as from power lines I50, I5I,and I52 controlled by a power line switch, passing through conductors tothree relays which control the three motors 1, 65, and I 08respectively.

From the power lines also current is furnished through conductors I 53and I54 to the primary of a control transformer, from the secondary ofwhich current is taken to operate the relays referred to, as well asothers entering into the control circuits.

In the transformer secondary circuit are located overload switchescontrolled by the cur rent supplied to motors, as well as a safety limitswitch, the operation of any one of which will break the main controlcircuit andso stop all operation of the mechanism.

From the secondary of the transformer, current is carried through aconductor I55 to a manually operable selective switch I51, and which maybe put either upon the contact hand" for manual control of the motors,or on the contact auto for the automatic control thereof.

Assuming that the parts are in their respective positions for starting acycle of operation, the slide will be retracted from the work to itsmaximum degree, and the carriage will be at the elevation at which thecut is completed. In this position, switches B and D will be opened andswitches A and C closed.

If switch I51 is placed on contact auto, current will pass directly atall times through conductors I6I and I13 to the coil of relay CR4,holding this, throughout automatic operation, to the right as seen inFigure 11.

If now the operator, after inserting a piece of work, presses the startbutton, current from the control transformer passes through the overloadswitches of the return and horizontal feed motors and conductor I55 tothe selective switch I51, thence to contact auto," thence throughconductor I58 to the start" switch, through this switch to conductors 2II, I85, and I15, by which it is carried to the coil of relay RRI,through switch C, thence through conductor I55, switch safety," and theoverload switches of the feed motor 1., back to the secondary of thecontrol transformer.

Simultaneously, some of the current passes through conductor I58, coilof relay CRI, which is arranged in parallel with the coil of relay RR,and conductor I51 to switch C. This moves the armatures of relays RBIand CRI to the right, as shown in the diagram, closing the contacts tosupply current from the power lines III, III, and I52 to the returnstroke motor 55, and thus causing this motor to operate, whereupon thevertically movable carriage is moved to the position to start cutting.

When the operator releases the start switch, current may pass throughconductors I55, I55, I50, and I10 through the then closed contacts ofrelay RBI and conductor I14 to maintain the coils of relay RRI and CRIenergized until switch C is opened. Thi occurs when the verticallymovable carriage has reached the position to start cutting, while duringthe motion or the carnage, switch B has been permitted to close. Theopening of switch C de-energizes relays RBI and CRI permitting thearmatures to return to the left as shown in the diagram.

In this portion of the cycle switches A and D are closed and current nowpasses through conductors I5I, I52 to the coil of relay CR3, thencethrough switch D to line I55, moving relay CR8 to the right as shown inthe diagram, and permitting current to how through conductors I82, I8I,I8I, I11 and I54 to coil of relay HR, thence through switches A,conductor I85, switch "out"; thus reaching line I45, which actuatesmotor I08 to move the horizontal slide to the right, as shown in thedrawings, feeding the cutter into depth or against the stop. When thishas been accomplished, switch A is opened, while during the motion,switch C has been permitted to close, so that current now passes throughconductors I5I, I62 and I80, coil CR8 to line I55, and also throughconductors I82, I8I, I88, 208, and I58 to coil of relay CR2, thencethrough conductors 2I2, 2I8, and 2 to line I55.

Current also passes through conductor I8I, 200, I11, I64 and I55 to thecoil oi! relay FR. and thence to line I55, causing the feed motor 1 tooperate and feed the tool through the work.

During this portion of the cycle switch B again closes, while at the endof the cycle switch D is opened, so that the current now passes toconductors I82, I83, 208 and I58 to the coil of relay CR2 through switchB, conductor 2 to the line I55; which in turn permits current to passfrom conductor I8I through conductor 200, I11, I54 to the coil of relayHR, thence to conductor 204, 2I0, I95, I18, I84 and I95 to the switchout; where it connects line I 55, thus operating the motor I08 toretract the cutter from depth, at the end of which stroke switches B andD are again opened, stopping the operation of the parts until the startswitch is depressed and the cycle thus started over again.

When it is desired to actuate the apparatus by hand, switch I51 is movedto the contact hand, so that relay CR4 is de-energized and currentsupplied to conductor 205, thence through conductors 205, 201, and 208to the contacts'of the four manual switches shown at the left end in thedrawings.

If, now, the operator depresses the up switch, current flows throughconductors I01, I and I15 to the coil of relay RRI, thence throughswitch C to line I55, and simultaneously is conducted through conductorI55 to the coil of relay CRI and back to switch C, through conductorI51. This, of course, actuates motor 55 to move the vertical slide inthe direction of its normal return stroke.

If, instead, the operator depresses the "down" push button, currentpasses through conductor aaaaeaa its to the coil of relay RRE, thencethrough conductor lllt to switch D, and from this to line ltd, actuatingrelay RBI to operate motor 65 in a reverse direction.

When the operator pushes the in" button, current passes throughconductors I93, I9I, I'll and lllt to the coil of relay HR, throughswitch A, conductor I195 to switch out, where it reaches line I58.

Push out button merely reverses the last mentioned circuit, currentpassing through conductors I94, IBI, Ill and I64 to the coil of relayHR.

While the pitch of worms and 63 is low enough to prevent any substantialback drive through the same, and the dwell surfaces of the cam I04likewise are designed to preclude back drive, we have shown providedmagnetic brakes for locking each of the motors against rotation when itis not being operated, these being of a type which will be readilyunderstood by those skilled in the art, and being spring actuated, butheld in released position by current passing through a coil when currentis being supplied to the motor. The coils of these brakes areillustrated in Figure 11, that of the feed motor 'I being shown at FB,of the horizontal slide moving motor I09 at HB, and that of the returnmotor 85 at RB.

While we have described the illustrated embodiment of our invention insome particularity, obviously many other embodiments, variations andmodifications will readily occur to those skilled in this art, and we donot therefore limit ourselves to the precise details shown and describedherein, but claim as our invention all embodiments, variations, andmodifications coming within the scope of the appended claims.

We claim:

1. A machine tool comprising a frame, guideways thereon, a carriageslidable on said guideways, a spring between the frame and the carriagecapable of moving the carriage on the frame, a spindle carried by theframe, a spindle carried by the carriage, gearing between said spindles,a screw controlling the motion of the carriage on the frame, operativeconnections between said screw and said gearing, guideways on saidcarriage, a slide movable on said guideways, a stop limiting the motionof said slide, resilient means urging said slide toward said stop, andmeans for retracting said slide from said stop.

2. A hobblng machine comprising a frame, a spindle mounted in fixedbearings in said frame, a carriage slidable upon the frame, a slideslidably carried by the carriage, a spindle journalled on said slide, afeed screw between the frame and the carriage, gearing between saidspindles including a differential, a motor operatively connected to saidgearing, gearing between said first mentioned gearing and said feedscrew including a second differential, a motor operatively connected to.a part of said second mentioned differential, a spring interposedbetween the frame and the carriage, a stop carried by the carriage andlimiting the motion of the slide in one direction, a plunger for movingthe slide toward and from said stop, a spring interposed between saidplunger and said slide, a cam associated with said plunger, a motorarranged to rotate said cam, and automatic connections between saidmotors causing them to operate in sequence.

3. In a machine of the class described, comprising a stationary frame, awork spindle and a tool spindle carried thereby, said spindles beingrelatively movable in two directions, feed means 4. In a machine of theclass described, comprising a stationary frame, a work spindle and atool spindle carried thereby, said spindles bein relatively movable intwo directions, feed means moving said spindles relatively in onedirection, an electrical motor for operating said feed means, quickreturn means moving said spindles r latively in the opposite direction,a second motor for operating said quick return means, means feeding saidspindles into depth relative each other and retracting the samerelatively, a third electrical motor for operating said last mentionedmeans, relays controlling the operation of said motors, switchesassociated with said feed means, said return means and said depthfeeding means and arranged to control said relays automatically movingthe tool and work relatively through a closed cycle, and manualcontrolling means associated with and selectively controlling saidrelays.

5. A machine of the character described comprising two relativelymovable spindles, gearing between said spindles, feed means capable ofreciprocating said spindles relatively in one direction and controlledby said gearing, feed means capable of reciprocating said spindlesrelatively in another direction, two motors connected. to said firstmentioned feed means capable of operating the same at different speeds,a third motor operably connected to said second mentioned feed means,and electrical connections between said motors whereby said lastmentioned motor opcrates intermediate the operation of the two firstmentioned motors.

6. A machine of the character described comprising two relativelymovable spindles, gearing between said spindles, feed meansreciprocating said spindles relatively in one direction, gearing betweensaid feed means and said first mentioned gearing, a motor operativelyconnected to said first mentioned gearing, a motor operatively con-.nected to said second mentioned gearing, a second feed means forreciprocating the spindles relatively in another direction, a motoroperatively connected to said-last mentioned feed means, switchescontrolled by the relative motions of said spindles and automaticallycausing said motors to operate in sequence, the last mentioned motorbeing operated between periods of operation of the two first mentionedmotors.

7. A machine tool comprising a frame, upwardly extending guides thereon,a carriage slidable upon said guides, a spring interposed between theframe and carriage, and exerting sufficient upward pressure on thecarriage at all times to both support the weight of the carriage andcause its upward motion upon said guides, a pair of threaded elementslimiting the upward motion of the carriage, one associated with saidframe and the other with said carriage, holding 6 2,se4,oa2

support the weight of the carriage and cause its 10 upward motionupon'said guides, a positive stop fixed with relation to the frame, arigid element interposed between the stop and the carriage and arrangedpositively to limit the upward motion of the carriage, and driving meansactuating 15 said rigid element progressively to vary the position ofthe carriage on said guides.

9. A machine tool comprising a frame, upward- 1y extending guidesthereon, a carriage slidable upon said guides, a spring interposedbetween the frame and carriage, and exerting lsuiilcierlt upwardpressureon the carriage at all times to both support the weight of thecarriage and cause its upward motion upon said guides, a pair of threaded elements limiting the upward motion of the carriage, one associatedwith said frame and the other with said carriage. holding meanspositively locating one of said threaded elements with respeet to theframe, driving means capable of producing relative rotation between saidthreaded elements. a spindle carried by the frame, a second spindlecarried by said carriage, positive gearing between said spindles, andpositive driving connections between said gearing and said threadedelements.-

HOMER. C. WARNER.

CHARLES H. SCHURR.

